142-50.Tuning a tunnel-diode oscillator bychanging the capacitance of the tunedcircuit can be accomplished by which ofthe following tuning methods?1.Bias tuning2.Slot tuning3.Current tuning4.Varactor tuning2-51.In the reflection-type, circulator-coupledtunnel-diode amplifier, what componentprevents feedback to the tuned inputcircuit?1.The circulator2.The output loop3.The tuned cavity4.The tunnel diode2-52.Stability is a problem in which, if any, ofthe following tunnel-diode frequencyconverters?1.High-gain converter2.Unity-gain converter3.Conversion-loss converter4.None of the above2-53.The varactor is a type of pn junction thatacts as which of the following types ofelectronic devices?1.Fixed resistor2.Fixed capacitor3.Variable resistor4.Variable capacitor2-54.What is the most important feature of theparametric amplifier?1.Low noise2.High gain3.Power output4.Frequency rangeFigure 2A.Voltage amplification circuit.IN ANSWERING QUESTION 2-55, REFERTO FIGURE 2A.2-55.How is amplification accomplished in thecircuit?1.By opening the switch2.By varying the frequency3.By varying the resistance4.By varying the capacitance2-56.In a nondegenerative parametricamplifier, how does the pump frequencycompare to the input signal frequency?1.The pump frequency is half the inputsignal frequency2.The pump frequency is double theinput signal frequency3.The pump frequency is more thandouble the input signal4.The pump frequency is equal to theinput signal frequency2-57.In a nondegenerative parametricamplifier with a pump frequency of 12gigahertz and an idler frequency of 9gigahertz, what is the input signalfrequency?1. 3 gigahertz2. 18 gigahertz3. 21 gigahertz4.108 gigahertz